EvtMelikhovFF.cc

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 1998      Caltech, UCSB
//
// Module: EvtMelikhovFF.cc
//
// Description: form factors for B->D*lnu according to HQET
//
// Modification history:
//
//    DJL     April 17, 1998        Module created
//
//------------------------------------------------------------------------
//
#include "EvtMelikhovFF.hh"
#include "../EvtGenBase/EvtId.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include <math.h>
#include <string>
 
EvtMelikhovFF::EvtMelikhovFF( double arg1 ) {
 
  whichfit = int( arg1 + 0.1 );
  return;
}
 
void EvtMelikhovFF::getvectorff( EvtId parent, EvtId daught, double t, double mass,
                                 double* a1f, double* a2f, double* vf, double* a0f ) {
 
  double ma1( 0.0 ), ra1( 0.0 ), na1( 0.0 );
  double ma2( 0.0 ), ra2( 0.0 ), na2( 0.0 );
  double mv( 0.0 ), rv( 0.0 ), nv( 0.0 );
 
  if ( whichfit == 1 )
  {
    ma1 = 7.07;
    ra1 = 0.27;
    na1 = 2.65;
    ma2 = 6.13;
    ra2 = 0.25;
    na2 = 2.17;
    mv  = 6.28;
    rv  = 0.30;
    nv  = 2.36;
  }
  if ( whichfit == 2 )
  {
    ma1 = 6.78;
    ra1 = 0.20;
    na1 = 2.65;
    ma2 = 6.00;
    ra2 = 0.19;
    na2 = 2.34;
    mv  = 6.22;
    rv  = 0.20;
    nv  = 2.46;
  }
  if ( whichfit == 3 )
  {
    ma1 = 6.50;
    ra1 = 0.21;
    na1 = 2.70;
    ma2 = 5.90;
    ra2 = 0.20;
    na2 = 2.45;
    mv  = 5.90;
    rv  = 0.21;
    nv  = 2.35;
  }
  if ( whichfit == 4 )
  {
    ma1 = 5.68;
    ra1 = 0.29;
    na1 = 1.67;
    ma2 = 5.36;
    ra2 = 0.28;
    na2 = 1.67;
    mv  = 5.46;
    rv  = 0.29;
    nv  = 1.73;
  }
 
  double mb = EvtPDL::getMeanMass( parent );
  // double w = ((mb*mb)+(mass*mass)-t)/(2.0*mb*mass);
 
  double melr = mass / mb;
  double mely = t / ( mb * mb );
 
  *a1f = ( ( 1.0 + melr * melr - mely ) / ( 1 + melr ) ) * ra1 /
         pow( 1.0 - ( t / ( ma1 * ma1 ) ), na1 );
  *a2f = ( 1 + melr ) *
         ( ( 1.0 - melr * melr - mely ) / ( ( 1 + melr ) * ( 1 + melr ) - mely ) ) * ra2 /
         pow( 1.0 - ( t / ( ma2 * ma2 ) ), na2 );
  *vf  = ( 1 + melr ) * rv / pow( 1.0 - ( t / ( mv * mv ) ), nv );
  *a0f = 0.0;
 
  return;
}